Circuit breaker for high voltage



March '9, 1943. H. A. H. NIJLAND 2,313,571

CIRCUIT BREKER FOR HIGH VOLTAGE Filed July 7, 1939 /f /am gj/w, h4/M Patented Mar. 9, 1943 2,313,571 CIRCUIT BREAKER FOR HIGH VCLTAGE Hendrik A. Hidde Nijland, Laren,

vested in the Alien Property Netherlands Custodian Application July 7, 1939, Serial No. 283,273 In the Netherlands July 12, 1938 4 Claims.

This invention relates to a circuit-breaker for high voltage, of which the contact make and break element, consisting of Xed contacts and of a movable conductor `co-operating therewith, is accommodated in a fixed metal tank which is provided with xed leading-in conductors passing through insulators in the wall thereof and is adapted to be filled with an insulating iiuid, such as mineral oil, or to contain a gas, the makeand break element being connected to the leading-in conductors, in such manner that said element can be entirely withdrawn :from and inserted into the tank, while the leading-in conductors are alive.

In circuit-breakers of the above type the arc products such as metallic, carbon and/or brous particles, are forced by a iiow of liquid or gas set up by mechanical means or by the pressure created within the casing or chamber, in which the breaking of the circuit occurs, through vents in the wall of said casing or through Openings in the stationary contacts into the space surrounding the casing. These particles, however, may deposit on the inner wall of the tank or on the surfaces of the insulators, through which the leading-in conductors enter said tank, and may form creep-ways for the electricity on said surfaces. Besides, if an insulating liquid, such as mineral oil, is contained in the tank, small particles are retained in suspension and unfavourably aiTect the insulating capacity of said liquid. Thus, where a circuit breaker operates frequently and/or under unfavorable conditions, there exists a danger of rupturing the dielectric near the surfaces of the leading-in insulator and, if insulating liquid is used, also at other points in the tank, This danger necessitates continuous supervision and, when necessary, cleaning of the insulator surfaces. In the case of liquid insulation, repeated renewal thereof may also be necessary.

Since the insulators of the leading-in conductors of a circuit-breaker can only be cleansed when these conductors have been rendered dead, it is generally preferred to connect a circuit.- breaker and even a circuit-breaker of the type, which has originally been designed for use without isolating switches and for which purpose the contact make and break element of said circuitbreaker can be entirely withdrawn from and inserted into the tank, while the leading-in conductors are alive, with the live network through one or two isolating switches.

The invention has for its object to avoid these disadvantages* It consists in that the contact make and break element is surrounded by a casing of insulating material, which completely isolates the space in which the switching operation is carried out from the compartment which the leading-in conductors enter, so that no arc products can be thrown into the latter compartment and spoil the insulation therein.

In order that the above statement may be more fully understood, reference is had to the drawing, which, by way of example only shows an embodiment of the invention partially in a vertical sectional view.

In the embodiment shown, the tank consists of two tubular casings I `and 2 communicating with one another at their `top ends and having the tubular insulators 3a and 4a for the leading-in conductors 3 and 4 mounted in their respective bottoms. The tank is lled with mineral koil 5, The contact make and break element is secured to the cover 6 of the tank and immersed in said oil.

The contact make and break element is ac commodated in a tube 'l of insulating material, which is closed at its lower end by a plate 8. Mounted on the top end of tube 1 is a funnelshaped metal member 9. Secured to the plate 8 is a fixed switch contact III and a contact sleeve II, directly electrically connected thereto. The contact sleeve II engages the plug shaped top end of the leading-in conductor, the bottom end of which is connected to one of the three dis,- tributing busbars I2 mounted in a separate casing I3.

Within the tube 1, a second xed switch contact I4 is mounted some distance above the xed switch contact IIJ, said contact I4 being secured to the cover 6 by means of insulators I5 and I6. The switch contacts I9 and I4 cooperate with a switching conductor 25 adapted to be axially moved by an operating mechanism (not shown) enclosed in a box I'I mounted on the cover 6.

The switching contact I4 is conductively connected, through a bridging conductor I8, to a second contact sleeve I 9, which engages the plugshaped top end of the leading-in conductor 4, whose lower end is connected to a cable 20. The contact sleeve I9 is supported by a plate, which closes the lower end of a tubular insulator 2l secured to the cover 6.

The horizontal portion of the bridging conductor I8 is surrounded bya tube 22 of insulating material, which tube is passed through the wall of the funnel-shaped metal member 9.

The parts 1, 9, 2l and 22 are filled with mineral oil 23. This oil, in which the switching operation is carried out, is entirely separated from the oil 5 in the tank, which serves to insulate the live parts of the circuit-breaker from the metal walls ofthe tank.

It is not necessary for the insulating fluids to be of the same composition. Also, the invention is not restricted to the use of liquid insulating materials only.

The tube 'l should be constructed to resist the heavy shocks or stresses which occur when large power circuits are broken.

If the insulating fluid 5 is a liquid, its incompressibility can be used to reinforce the tube 1. For that purpose, the casing I of the illustrated circuit-breaker is closed by a partition 24 provided with vents 25, which are so small as to prevent liquid to pass during the switching explosion (1/200 sec.). Since the partition 24 is mounted below the level of the liquid 5, the lower part of the casing l will always be entirely filled with liquid, which is essential with a View to the purpose aimed at.

What I claim is:

l. A metal-clad circuit breaker for high voltage, comprising a fixed metal tank, an insulating liquid such as mineral oil contained in said tank, insulators in the wall of said tank, fixed leadingin conductors passed through said insulators and extending with one of their ends into said tank,

a contact make-and-break element comprising fixed switch contacts and a movable contact cooperating therewith, contact means connected both electrically conductively and mechanically rigidly to said fixed switch contacts, contact means provided at said conductors, the contact means connected to the fixed switch contacts and those provided at the leading-in conductors releasably engaging one another so as to permit the contact make-andbreak element to be entirely withdrawn from and inserted into the tank while the leading-in conductors are alive, a casing of insulating material dividing the tank into a space in which the switching operation is carried out and a compartment which the leading-in conductors enter and completely isolating said space from said compartment, and a partition dividing said compartment into parts, one of which surrounds said casing and is completely or substantially completely closed and entirely filled with the insulating liquid, the said partition being mounted below the level of the liquid in the part of the tank outside the casing and being provided with at least one very small vent.

2. A metal-clad circuit breaker for high voltage, comprising a fixed metal tank, an insulating fluid in said tank, insulators in the wall of said tank, xed leading-in conductors extending into said tank, a contact make-and-break element comprising fixed switch contacts and a movable contact cooperating therewith, contact means connected both electrically conductively and mechanically rigidly to said fixed switch contacts, contact means provided at the ends of the leading-in conductors in said tank, the contact means connected to the fixed switch contacts and those provided at the leading-in conductors releasably engaging one another so as to permit the Contact make-and-break element to be entirely withdrawn from and inserted into the tank while the leading-in conductors are alive, and a casing of insulating material retractably accommodated in said tank and dividing the tank into a space in which the switching operation is carried out and a completely separate compartment into ends of the leading-in which the leading-in conductors enter, said casing being removable from said tank simultaneously with said make-and-break element, said compartment surrounding said casing of insulating material and providing between the latter and said metal tank suflicient insulating fluid to withstand the potential difference between live parts and the metal tank, whereby special auxiliary insulating switches are rendered superiiuous.

3. A metal-clad circuit breaker for high voltage, comprising a fixed metal tank, an insulating fluid in said tank, insulators in the wall of said tank, fixed leading-in conductors extending into said tank, a contact make-and-break element comprising fixed switch contacts and a movable contact cooperating therewith, contact means connected both electrically conductively and mechanically rigidly to said fixed switch contacts, contact means provided at the ends of the leading-in conductors in said tank, the contact means connected to the fixed switch contacts and those provided at the leading-in conductors releasably engaging one another so as to permit the contact make-and-break element to be entirely withy drawn from and inserted into the tank while the leading-in conductors are alive, a casing of insulating material retractably accommodated in said tank and dividing the tank into a space in which the switching operation is carried out and a compartment into which the leading-in conductors enter, said casing being removable from said tank simultaneously with said make-andbreak element, and a partition dividing said compartment into parts one of which surrounds said casing and is substantially completely closed and entirely filled with insulating fluid suilicient to withstand the potential difference between live parts and said metal tank, whereby special auxiliary insulating switches are rendered superfluous.

4. A metal-clad circuit breaker for high voltage, comprising a fixed metal tank, an insulating fluid in said tank, insulators at spaced points in the wall of said tank, fixed leading-in conductors extending through said insulators into said tank, a contact make-and-break element comprising fixed switch contacts and a movable contact cooperating therewith, contact means connected both electrically conductively and mechanically rigidly to said fixed switch contacts, at least one of said last named connections being effected through the medium of an elongated bridging member, contact means provided at the ends of the leading-in conductors in said tank, the contact means connected to the fixed switch contacts and those provided at the leading-in conductors releasably engaging one another so as to permit the contact make-and-break element to be entirely withdrawn from and inserted into the tank while the leading-in conductors are alive, and a casing of insulating material retractably accommodated in said tank and dividing the tank into a space in which the switching operation is carried out and a completely separate compartment into which the leading-in conductors enter, said casing being removable from said tank simultaneously with said make-and-break element, and said compartment surrounding said casing of insulating material and providing between the latter and said metal tank suillcient insulating fluid to withstand the potential difference between live parts and the metal tank, whereby special auxiliary insulating switches are rendered superfluous.

HENDRIK A. HIDDE NIJ LAND. 

